Binaryworld - Get IP from Host Name. ... [ VB -> Networking ]

This example will show you how to get IP address from host name and also How to retrive all associated IPs to your local machine.

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Private Type HOSTENT
  h_name As Long
  h_aliases As Long
  h_addrtype As Integer
  h_length As Integer
  h_addr_list As Long
End Type
Private Const AF_INET = 2
Private Declare Function gethostbyname _
    Lib "WSOCK32.DLL" (ByVal name As String) As Long
Private Declare Function gethostname _
    Lib "WSOCK32.DLL" (ByVal hostname$, ByVal HostLen As Long) As Long
Private Declare Function inet_ntoa _
    Lib "WSOCK32.DLL" (ByVal inaddr As Long) As Long
Private Declare Sub CopyMemory _
    Lib "kernel32.dll" Alias "RtlMoveMemory" (Destination As Any _
    , Source As Any, ByVal length As Long)
Private Declare Function lstrlen _
    Lib "kernel32.dll" Alias "lstrlenA" (ByVal lpString As Any) As Long
Private Declare Function lstrcpy _
    Lib "kernel32.dll" Alias "lstrcpyA" (ByVal lpString1 As Any, ByVal _
    lpString2 As Any) As Long

Private Sub Form_Load()
  MsgBox GetIpFromName("WWW.google.com")
  MsgBox GetAllLocalIP
End Sub

Function GetIpFromName(hostname As String) As String
  Dim hostinfo As HOSTENT                ' information about an Internet host
  Dim pHostinfo As Long                 ' pointer to a HOSTENT structure
  Dim pIPAddress As Long                 ' pointer to an IP address dword
  Dim ipAddress As Long                 ' an IP address, packed into a dword
  Dim pIPString As Long                 ' pointer to an IP address formatted as a string
  Dim ipString As String                 ' holds a human-readable IP address string
  Dim retval As Long                   ' generic return value

  'HostName = InputBox("Enter hostname to resolve", "[Hostname to IP demo]", "www.google.com")

  ' Get information about the domain specified in txtDomain.
  pHostinfo = gethostbyname(hostname)
  If pHostinfo = 0 Then
    'MsgBox "Unable to resolve domain name."
  Else
    'Copy the data into a HOSTENT structure.
    CopyMemory hostinfo, ByVal pHostinfo, Len(hostinfo)
    If hostinfo.h_addrtype <> AF_INET Then
      'MsgBox "A non-IP address was returned."
      Debug.Print "A non-IP address was returned."
    Else
      ' Copy the pointer to the first (and probably only) IP address in the structure.
      CopyMemory pIPAddress, ByVal hostinfo.h_addr_list, 4

      ' Copy the actual IP address.
      CopyMemory ipAddress, ByVal pIPAddress, 4
      ' Convert the IP address into a human-readable string.
      pIPString = inet_ntoa(ipAddress)
      ' Copy the result into a string variable.
      ipString = Space(lstrlen(pIPString))
      retval = lstrcpy(ipString, pIPString)
      ' Print the result: a human-readable IP address.
      'MsgBox HostName & " >> " & ipString
      GetIpFromName = ipString
    End If
  End If

End Function

Private Sub GetAllLocalIP()
  Dim hostname As String * 256
  Dim hostent_addr As Long
  Dim host As HOSTENT
  Dim hostip_addr As Long
  Dim temp_ip_address() As Byte
  Dim i As Integer
  Dim ip_address As String

  ' local machine name
  If gethostname(hostname, 256) = -1 Then
    MsgBox "Windows Sockets error "          '& Str(WSAGetLastError())
    Exit Sub
  Else
    hostname = Trim$(hostname)
  End If

  hostent_addr = gethostbyname(hostname)

  If hostent_addr = 0 Then
    MsgBox "Winsock.dll is not responding."
    Exit Sub
  End If

  CopyMemory host, ByVal hostent_addr, LenB(host)
  CopyMemory hostip_addr, ByVal host.h_addr_list, 4

  MsgBox hostname

  'get all of the IP address if machine is multi-homed
  Do
    ReDim temp_ip_address(1 To host.h_length)
    CopyMemory temp_ip_address(1), ByVal hostip_addr, host.h_length

    For i = 1 To host.h_length
      ip_address = ip_address & temp_ip_address(i) & "."
    Next
    ip_address = Mid$(ip_address, 1, Len(ip_address) - 1)

    MsgBox ip_address

    ip_address = ""
    host.h_addr_list = host.h_addr_list + LenB(host.h_addr_list)
    CopyMemory hostip_addr, ByVal host.h_addr_list, 4
  Loop While (hostip_addr <> 0)

End Sub